16168625 Tuning

Biggdaddy1962 · Post by **Biggdaddy1962** » Tue Jan 17, 2012 4:13 am

I am working on a 93 Silverado that I have installed a vortec headed 383 with a very mild cam(.431,.451 & 196/206), air gap intake and shorty headers. I am using the stock tbi for now with a spring change to get the pressure to 16psi. Looking at the VE table in the stock BHAR chip shows numbers in the 96% range. I know this is "BS" for a stock tbi 350. If I make any significant changes here the numbers will be over 100%. Looking at a bin file for my son's 91 truck w/tbi the VE table numbers are much lower and more realistic. I am very new to this so if I am out in left field please let me know. Do I need to change the multiplier in the .XDF file and the numbers in the VE table to give me a better starting point for easier changes? The truck cranks up and runs O.K. while in open loop but once it goes into closed loop it gets very lean. I have changed the cylinder volume and injector constant in the bin but have not made any other changes. It's a 16168625 ecm. Any help or insight prior taking the next step would be appreciated.

EagleMark · Post by **EagleMark** » Tue Jan 17, 2012 5:46 pm

Every Mask/XDF is differant. The 1991 is usally a 1227747 $42 which uses Main VE and Adder VE. If you add the 2 together they come up over 100%. I know that's wrong but that is how it comes from GM.

You do have correct xdf?

http://www.gearhead-efi.com/Fuel-Inject ... up-Project

Biggdaddy1962 · Post by **Biggdaddy1962** » Wed Jan 18, 2012 5:37 am

The xdf i am using is the "Advanced $E6 TP5 v250.xdf" you helped me find in an earlier post. Everything else in the Parameter Summary List looks correct. I looked at changing the scaling but many of the numbers in the hex bin are close to 256 or FF so no joy there. Does it make sense to reduce the injector constant and richen it up to the point I will need to lower the VE Table numbers to fine tune? Thanks.....

EagleMark · Post by **EagleMark** » Wed Jan 18, 2012 6:33 am

We have found PE Power Enrichement to be almost impossible to obtain, this may be your answer if your running lean WOT with VE numbers that high.
http://www.gearhead-efi.com/Fuel-Inject ... ot-working

Also a modified engine may not have enough fuel, you may need to bump up fuel pressure. If you have estimated HP for your engine build you can use an ijector sizing spreadsheet to get an idea of fuel pressure needed with injectors.
http://www.gearhead-efi.com/Fuel-Inject ... tor+sizing

Post by **robertisaar** » Wed Jan 18, 2012 10:44 am

GM has this bad habit of using REALLY out-there VE numbers in pretty much any calibration.

in the masks that use BPC numbers, that's pretty much the only way to try and get it correct, is it bias the BPC (or BPC vs EGR). the masks that use a cylinder size and true "injector flowrate" value, it feels kinda wrong to make those values incorrect, but there's not much else you can do.

personally, i would skew cylinder size first, since messing with the injector flowrate value may effect more than just base fueling.